Which chemicals readily enter the atmosphere as gases, mainly from evaporation?

Which chemicals readily enter the atmosphere as gases, mainly from evaporation?

• A. Particulates
• B. Nitrogen oxides
• C. Volatile organic compounds
• D. Sulfur dioxide

Answer: (C)

Volatility and evaporation determine whether a substance will enter the air as a gas. Substances with high vapor pressure at room temperature readily evaporate from liquids, so they escape into the atmosphere as gases. These are volatile organic compounds, or VOCs, which come from sources like solvents, paints, fuels, and even some plants. That quick transition from liquid to gas means VOCs are emitted directly into the air by evaporation. In contrast, particulates are tiny solid or liquid particles suspended in the air, not gases, and they’re produced by processes like combustion or mechanical wear. Nitrogen oxides and sulfur dioxide are gases, but they’re mainly formed during high-temperature combustion and industrial processes, not primarily by evaporation of liquids. So VOCs best fit the idea of entering the atmosphere readily as gases from evaporation.

Volatility and evaporation determine whether a substance will enter the air as a gas. Substances with high vapor pressure at room temperature readily evaporate from liquids, so they escape into the atmosphere as gases. These are volatile organic compounds, or VOCs, which come from sources like solvents, paints, fuels, and even some plants. That quick transition from liquid to gas means VOCs are emitted directly into the air by evaporation.

In contrast, particulates are tiny solid or liquid particles suspended in the air, not gases, and they’re produced by processes like combustion or mechanical wear. Nitrogen oxides and sulfur dioxide are gases, but they’re mainly formed during high-temperature combustion and industrial processes, not primarily by evaporation of liquids. So VOCs best fit the idea of entering the atmosphere readily as gases from evaporation.